Four Turkish soldiers were killed Monday when their military helicopter crashed in a residential neighborhood in Istanbul. The helicopter went down in a residential area while trying to make an emergency landing on the grounds of a building complex on the Asian side of Istanbul. Television images showed smoke rising from the area and ambulances rushing to the scene. There were no civilian injuries or casualties, Istanbul Governor Ali Yerlikaya said told reporters, adding that the cause of the crash was not yet known. Yerlikaya said prosecutors and the Turkish military have launched separate investigations into the cause of the crash.